On Mon, May 30, 2016 at 04:48:36PM +0800, baotiao wrote: > how can I set the extent size hint to a file with command line? > > I have google for a lot, but I can't find a answer > It can be set with xfs_io, like: xfs_io -c "extsize 8m" <file> # To set an extent size hint of 8m Although, it only works if the file is empty, or more specific, the file must not have any extents allocated > ---------------------------------------- > > Github: [1]https://github.com/baotiao > Blog: [2]http://baotiao.github.io > Stackoverflow: [3]http://stackoverflow.com/users/634415/baotiao > Linkedin: [4]http://www.linkedin.com/profile/view?id=145231990 > > On May 30, 2016, at 13:04, Dave Chinner <[5]david@xxxxxxxxxxxxx> wrote: > > On Mon, May 30, 2016 at 12:45:07PM +0800, baotiao wrote: > > This machine is running for qemu, the file is qemu qcow file type > [root@w-openstack20 > /data/nova/instances/7898b630-c4ef-49ab-9ce9-3735e090c282]# file > disk > disk: QEMU QCOW Image (v3), has backing file (path > /data/nova/instances/_base/3f27393376152ac352b2d85703011e38517e), > 429496729600 bytes > > Oh, you're using delta/snapshot based qcow images. That, by it's > very nature, generates fragmented image files as they are a delta > over the backing file. > .... > > actual 48421430, ideal 20716, fragmentation factor 99.96% > How can I solve this problem, what do you suggest me to do? > > Use a extent size hint (say 1-8MB) for your qcow2 image files so that > they don't fragment badly as they are written to. > Cheers, > Dave. > -- > Dave Chinner > [6]david@xxxxxxxxxxxxx > > References > > 1. https://github.com/baotiao > 2. http://baotiao.github.io/ > 3. http://stackoverflow.com/users/634415/baotiao > 4. http://www.linkedin.com/profile/view?id=145231990 > 5. mailto:david@xxxxxxxxxxxxx > 6. mailto:david@xxxxxxxxxxxxx > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs -- Carlos _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
